DeepOcean done with South China Sea trenching

DeepOcean UK has completed its part of works at the Liwan 3-1 project, offshore China.

Liwan 3-1 is part of the Liwan gas project, 300 km southeast of the Hong Kong Special Administrative Region, that also includes Liuhua 34-2 and Liuhua 29-1 fields. All three fields share a subsea production system, subsea pipeline transportation, and onshore gas processing infrastructure.

DeepOcean started works on the project for COOEC Subsea in March 2012.

The Volantis vessel and UT-1, the world’s most powerful free-flying jet trencher according to the company, conducted trenching and survey operations over 160km of the 30” Liwan Pipeline connecting the Liwan Central Platform (CEP) in 200m water-depth to the shore at China National Offshore Oil Corporation’s (CNOOC) Gaolan gas plant.

Prior to trenching, activities included construction works involving crossings along the pipeline route utilizing the WROVs and technicians onboard Volantis to deploy over 100 mattresses along the pipeline in preparation for the lay campaign. Trenching activities with the UT-1 and dedicated crew achieved burial depths along the route deploying the UT-1 jetting swords to 2.5m below the seabed for trenching of the large diameter pipeline.

Liwan platform

Upon completion of trenching activities in August 2013 in the shallow water section of the project for COOEC Subsea, Volantis was immediately contracted by Saipem to perform subsea field development activities in the deep water section of the Liwan 3-1 field operating ROVs in excess of 1,400m water depth.

DeepOcean was responsible for various tasks infield working closely with clients to deliver safe and efficient subsea operations.

The company has explained that Volantis’ superior sea-keeping capability and innovative launch and recovery systems onboard allowed both contracts with COOEC and Saipem to operate continuously through the harsh monsoon seasons with minimal downtime operating under contract for a continuous period of over 875 days.

Tony Stokes, Director of Asia Pacific for DeepOcean said: “It was a privilege to be part of such a momentous project in China. Working on both segments of China’s first deep-water field development displays the confidence our clients have in DeepOcean’s ability to deliver trenching solutions along with diver-less construction work scopes in the dynamic Asia Pacific Region.”